Name:_________________________________Date:________________________

1. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bWhich%20of%20the%20following%20best%20describes%20the%20pattern%20%7d264,\,252,\,240,\,...\,?

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A.

https://media.studyisland.com/cgi-bin/mimetex.cgi?n\,-\,12,\,n\,-\,24,\,n\,-\,36,\,...

 

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B.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7bn%7d%7b2%7d\,,\,\frac%7bn%7d%7b3%7d\,,\,\frac%7bn%7d%7b4%7d\,,\,...

 

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C.

https://media.studyisland.com/cgi-bin/mimetex.cgi?2n,\,3n,\,4n,\,...

 

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D.

https://media.studyisland.com/cgi-bin/mimetex.cgi?n\,+\,12,\,n\,+\,24,\,n\,+\,48,\,...


2. The first five terms of a sequence are given below.

83 , 71 , 59 , 47 , 35 , ...

What is the next term of the sequence?

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A.

25

 

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B.

23

 

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C.

22

 

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D.

24


3. Look at the pattern below.

50, 100, 200, 400, ...

Which number sentence can be used to determine n, the 9th number in the pattern?

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A.

n = 25 × 92

 

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B.

n = (25 × 9) - 1

 

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C.

n = 25 × 29

 

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D.

n = 25 ÷ 9



 

4. The first three patterns of a sequence of dots is shown below.

https://app30.studyisland.com/pics/63900pattern1.png


If the pattern continues indefinitely, which of the following expressions can be used to determine the number of dots in the nth term of the sequence?

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A.

n(n + 3)

 

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B.

n(n + 1)

 

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C.

3n

 

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D.

n2 + 3


5. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bWhich%20of%20the%20following%20best%20describes%20the%20pattern%20%7d4,\,8,\,16,\,...\,?

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A.

https://media.studyisland.com/cgi-bin/mimetex.cgi?2n,\,4n,\,6n,...

 

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B.

https://media.studyisland.com/cgi-bin/mimetex.cgi?%7b2%7d%5e%7bn%7d,\,%7b4%7d%5e%7bn%7d,\,%7b6%7d%5e%7bn%7d,\,...

 

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C.

https://media.studyisland.com/cgi-bin/mimetex.cgi?%7bn%7d%5e%7b2%7d,\,%7bn%7d%5e%7b3%7d,\,%7bn%7d%5e%7b4%7d,\,...

 

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D.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7bn%7d%7b2%7d\,,\,\frac%7bn%7d%7b4%7d\,,\,\frac%7bn%7d%7b6%7d\,,\,...


6. The first four terms of a sequence are given below.

10, 8, 6, 4, ...

What is the eighth term of the sequence?

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A.

4

 

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B.

-6

 

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C.

-2

 

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D.

-4



 

7. Which of the following patterns is determined from the expression below?

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7b1%7d%7b4%7d\%20+\%20\frac%7b2%7d%7b7%7dn

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A.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7b15%7d%7b28%7d\%20,\%20\frac%7b23%7d%7b28%7d\%20,\%201\,\frac%7b3%7d%7b28%7d\%20,\%201\,\frac%7b11%7d%7b28%7d\%20,\%20.\,.\,.

 

Bubble

B.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7b1%7d%7b4%7d\%20,\%20\frac%7b15%7d%7b28%7d\%20,\%20\frac%7b23%7d%7b28%7d\%20,\%201\,\frac%7b3%7d%7b28%7d\%20,\%20.\,.\,.

 

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C.

https://media.studyisland.com/cgi-bin/mimetex.cgi?-\frac%7b1%7d%7b28%7d\%20,\%20-\frac%7b9%7d%7b28%7d\%20,\%20-\frac%7b17%7d%7b28%7d\%20,\%20-\frac%7b25%7d%7b28%7d\%20,\%20.\,.\,.

 

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D.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7b15%7d%7b28%7d\%20,\%20\frac%7b11%7d%7b14%7d\%20,\%201\,\frac%7b1%7d%7b28%7d\%20,\%201\,\frac%7b2%7d%7b7%7d\%20,\%20.\,.\,.


8. The first three patterns of a sequence of dots are shown below.

https://app30.studyisland.com/userfiles/patterndots.gif


If the pattern continues indefinitely, which of the following expressions can be used to determine the number of dots in the nth term of the sequence?

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A.

3n

 

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B.

n(n + 1)

 

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C.

n(n + 2)

 

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D.

n2 + 2


9. What is the eleventh term of the pattern below?

23, 32, 47, 68, 95, ...

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A.

433

 

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B.

383

 

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C.

343

 

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D.

86



 

10. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bWhich%20of%20the%20following%20best%20describes%20the%20pattern%20%7d10,\,20,\,30,\,...\,?

Bubble

A.

https://media.studyisland.com/cgi-bin/mimetex.cgi?%7b10%7d%5e%7bn%7d,\,%7b15%7d%5e%7bn%7d,\,%7b20%7d%5e%7bn%7d,\,...

 

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B.

https://media.studyisland.com/cgi-bin/mimetex.cgi?n\,+\,5,\,n\,+\,7,\,n\,+\,9\,...

 

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C.

https://media.studyisland.com/cgi-bin/mimetex.cgi?2n,\,3n,\,4n,\,...

 

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D.

https://media.studyisland.com/cgi-bin/mimetex.cgi?2n,\,4n,\,6n,\,...


11. The first five terms of a sequence are given below.

20 , 27 , 34 , 41 , 48 , ...

Determine which of the following formulas gives the nth term of this sequence.

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A.

27 - 7n

 

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B.

13 + 7n

 

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C.

26 - 6n

 

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D.

14 + 6n


12. Which expression can be used to determine the nth term in the pattern below?

-5, -26, -61, -110, -173, ...

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A.

7n2 - 2

 

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B.

-7n + 2

 

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C.

-5n - 7

 

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D.

-7n2 + 2


13. The first five terms of a sequence are given below.

18 , 22 , 26 , 30 , 34 , ...

What is the next term of the sequence?

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A.

36

 

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B.

37

 

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C.

38

 

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D.

39


14. What is the sixth term in the pattern below?

19, 10, 1, -8, ...

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A.

-159

 

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B.

-26

 

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C.

-114

 

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D.

-17


15. What is the eighth term of the pattern below?

16, 35, 54, 73, ...

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A.

49

 

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B.

155

 

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C.

149

 

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D.

1,213


16. All points from which of the following patterns would be contained on the given graph?

 

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A.

-1 , 1 , 3 , 5 , ...

 

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B.

-7 , -11 , -15 , -19 , ...

 

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C.

-5 , -7 , -9 , -11 , ...

 

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D.

-6 , -9 , -12 , -15 , ...



 

17. The first three patterns of a sequence of dots are shown below.

https://app30.studyisland.com/pics/63900pattern2.png


If the pattern continues indefinitely, which of the following expressions can be used to determine the number of dots in the nth term of the sequence?

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A.

n(n + 3)

 

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B.

n(n + 5)

 

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C.

3n

 

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D.

n2 + 3


18. The first five terms of a sequence are given below.

39 , 43 , 47 , 51 , 55 , ...

Determine which of the following formulas gives the nth term of this sequence.

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A.

35 + 4n

 

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B.

43 - 4n

 

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C.

36 + 3n

 

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D.

42 - 3n


19. Which expression represents the total volume of the pictures shown if each cube has a side length of e?

https://app30.studyisland.com/userfiles/25593q17.png

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A.

c3 + e3

 

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B.

c3 · e

 

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C.

c · e3

 

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D.

c3 · e3



 

20. Which of the following patterns is represented by the graph below?

https://app30.studyisland.com/pics/150611question1.png

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A.

n2 - 4n - 3

 

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B.

n2 + 5n - 3

 

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C.

2n2 + n + 4

 

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D.

n2 - 5n - 3



 

Answers

1. A
2. B
3.
C
4.
D
5.
C
6.
D
7.
A
8. C
9.
B
10.
D
11.
B
12.
D
13.
C
14.
B
15.
C
16.
C
17.
A
18. A
19.
D
20.
D


 

Explanations

1. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bTo%20test%20one%20of%20the%20patterns,%20determine%20the%20number%20%7dn%20\text%7b%20that%7d\\\text%7bwill%20make%20the%20first%20term%20of%20the%20pattern%20equal%20to%20%7d264.\text%7b%20Then,%7d\\\text%7buse%20this%20number%20to%20calculate%20the%20other%20terms.%20The%20following%7d\\\text%7banswer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7beqnarray%7d\frac%7b(528)%7d%7b2%7d\,,\,\frac%7b(528)%7d%7b3%7d\,,\,\frac%7b(528)%7d%7b4%7d\,,\,...\,&=&\,264,\,176,\,132,\,...\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20(252)\,+\,12,\,(252)\,+\,24,\,(252)\,+\,48,\,...\,&=&\,264,\,276,\,300,\,...\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%202(132),\,3(132),\,4(132),\,...\,&=&\,264,\,396,\,528,\,...\end%7beqnarray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\text%7bThese%20answer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\\text%7bTry%20the%20remaining%20choice.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7barray%7d(276)\,-\,12,\,(276)\,-\,24,\,(276)\,-\,36,\,...\,&=&264,\,252,\,240,\,...%20%20\end%7barray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20\text%7bTherefore,%20the%20following%20pattern%20is%20the%20answer.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\n\,-\,12,\,n\,-\,24,\,n\,-\,48,\,...\\\end%7barray%7d

2. First, find the difference between terms.

71 - 83

= -12

59 - 71

= -12

47 - 59

= -12

35 - 47

= -12


Since the difference, -12, is constant, subtract 12 from the fifth term to find the next term.

35 - 12 = 23

3. The sequence of numbers given starts with 50. Look for a common difference.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\begin%7beqnarray%7d%20100\%20-\%2050\%20&=&\%2050\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\%20200\%20-\%20100\%20&=&\%20100\%20\end%7beqnarray%7d


There is no common difference, so look for a common ratio.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\begin%7beqnarray%7d%20\frac%7b100%7d%7b50%7d\%20&=&\%202\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\%20\frac%7b200%7d%7b100%7d\%20&=&\%202\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\%20\frac%7b400%7d%7b200%7d\%20&=&\%202\%20\end%7beqnarray%7d


There is a common ratio of 2, therefore this sequence is geometric.

Look at the sequence term by term and find a pattern in terms of number position.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\begin%7barray%7d%7brcccl%7d%20%7b\text%7b1%5e%7bst%7d%20term%7d%7d%20&%20%7b=%7d%20&%20%7b50%7d%20&%20%7b=%7d%20&%20%7b25\%20\times\%202%5e%7b1%7d\%20\text%7bor%7d\%2025\%20\times\%202%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\%20%7b\text%7b2%5e%7bnd%7d%20term%7d%7d%20&%20%7b=%7d%20&%20%7b100%7d%20&%20%7b=%7d%20&%20%7b25\%20\times\%202%5e%7b2%7d\%20\text%7bor%7d\%2025\%20\times\%204%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\%20%7b\text%7b3%5e%7brd%7d%20term%7d%7d%20&%20%7b=%7d%20&%20%7b200%7d%20&%20%7b=%7d%20&%20%7b25\%20\times\%202%5e%7b3%7d\%20\text%7bor%7d\%2025\%20\times\%208%7d\%20\end%7barray%7d


It appears that the jth term will equal 25 × 2j.

Therefore, the 9th number in the pattern will be 25 × 29.

4. Look at the sequence term by term and find the pattern in terms of the number position.

n = 1,

# of dots =

4

= 12 + 3 or 1 + 3

n = 2,

# of dots =

7

= 22 + 3 or 4 + 3

n = 3,

# of dots =

12

= 32 + 3 or 9 + 3


From looking at the patterns listed above, the number of dots is given by n2 + 3.

5. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bTo%20test%20one%20of%20the%20patterns,%20determine%20the%20number%20%7dn%20\text%7b%20that%7d\\\text%7bwill%20make%20the%20first%20term%20of%20the%20pattern%20equal%20to%20%7d4.\text%7b%20Then,%7d\\\text%7buse%20this%20number%20to%20calculate%20the%20other%20terms.%20The%20following%7d\\\text%7banswer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7beqnarray%7d2(2),\,4(2),\,6(2),\,...\,&=&\,4,\,8,\,12,\,...%20\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%7b2%7d%5e%7b2%7d,\,%7b4%7d%5e%7b2%7d,\,%7b6%7d%5e%7b2%7d,\,...\,&=&\,4,\,16,\,36,\,...\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20\frac%7b8%7d%7b2%7d\,,\,\frac%7b8%7d%7b4%7d\,,\,\frac%7b8%7d%7b6%7d\,,\,...\,&=&\,4,\,2\,,\,\frac%7b4%7d%7b3%7d\,,\,...\end%7beqnarray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\text%7bThese%20answer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\\text%7bTry%20the%20remaining%20choice.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7barray%7d%20\\%7b(2)%7d%5e%7b2%7d,\,%7b(2)%7d%5e%7b3%7d,\,%7b(2)%7d%5e%7b4%7d,\,...\,&=&4,\,8,\,16,\,...\,%20\end%7barray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20\text%7bTherefore,%20the%20following%20pattern%20is%20the%20answer.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\%7bn%7d%5e%7b2%7d,\,%7bn%7d%5e%7b3%7d,\,%7bn%7d%5e%7b4%7d,\,...%20\\\end%7barray%7d

6. First, find the difference between terms.

8 - 10

= -2

6 - 8

= -2

4 - 6

= -2


Since the difference, -2, is constant, subtract 2 from the fourth, fifth, sixth, and seventh terms to find the eighth term.

4 - 2

= 2

2 - 2

= 0

0 - 2

= -2

-2 - 2

= -4


Therefore, the eighth term of the sequence is -4.

7. Substitute n = 1, 2, 3, 4, ... into the expression to find the terms of the pattern.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\begin%7beqnarray%7d%20\frac%7b1%7d%7b4%7d\%20+\%20\frac%7b2%7d%7b7%7d(1)\%20&=&\%20\frac%7b15%7d%7b28%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\\frac%7b1%7d%7b4%7d\%20+\%20\frac%7b2%7d%7b7%7d(2)\%20&=&\%20\frac%7b23%7d%7b28%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\\frac%7b1%7d%7b4%7d\%20+\%20\frac%7b2%7d%7b7%7d(3)\%20&=&\%201\,\frac%7b3%7d%7b28%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\\frac%7b1%7d%7b4%7d\%20+\%20\frac%7b2%7d%7b7%7d(4)\%20&=&\%201\,\frac%7b11%7d%7b28%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d\\\%20\end%7beqnarray%7d

Therefore, the pattern determined from the expression is shown below.

https://media.studyisland.com/cgi-bin/mimetex.cgi?\frac%7b15%7d%7b28%7d\%20,\%20\frac%7b23%7d%7b28%7d\%20,\%201\,\frac%7b3%7d%7b28%7d\%20,\%201\,\frac%7b11%7d%7b28%7d\%20,\%20.\,.\,.

8. Look at the sequence term by term and find a pattern in terms of the number position.

n = 1,

# of dots =

3

= 1 × (1 + 2)

or 1 × 3

n = 2,

# of dots =

8

= 2 × (2 + 2)

or 2 × 4

n = 3,

# of dots =

15

= 3 × (3 + 2)

or 3 × 5


From looking at the patterns listed above, the number of dots is given by n × (n + 2).

Thus, the number of dots in the nth term of the sequence is given by n(n + 2).

9. The first and second differences of the sequence are shown below.

23

32

47

68

95

\

/

\

/

\

/

\

/

9

15

21

27

\

/

\

/

\

/

6

6

6


Since the second difference is constant, the pattern is quadratic with the form an2 + bn + c.

Set the second difference equal to 2a, and solve for a.

2a

=

6

a

=

3


Next, set the first term in the first difference equal to 3a + b, and solve for b.

3a + b

=

9

3(3) + b

=

9

9 + b

=

9

b

=

0


Finally, set the first term in the pattern equal to a + b + c, and solve for c.

a + b + c

=

23

3 + 0 + c

=

23

c

=

20


Thus, the sequence can be represented by 3n2 + 20.

Therefore, the eleventh term of the sequence is 3(11)2 + 20 = 383.

10. https://media.studyisland.com/cgi-bin/mimetex.cgi?\text%7bTo%20test%20one%20of%20the%20patterns,%20determine%20the%20number%20%7dn%20\text%7b%20that%7d\\\text%7bwill%20make%20the%20first%20term%20of%20the%20pattern%20equal%20to%20%7d10.\text%7b%20Then,%7d\\\text%7buse%20this%20number%20to%20calculate%20the%20other%20terms.%20The%20following%7d\\\text%7banswer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7beqnarray%7d2(5),\,3(5),\,4(5),\,...\,&=&\,10,\,15,\,20,\,...%20\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20(5)\,+\,5,\,(5)\,+\,7,\,(5)\,+\,9\,...\,&=&\,10,\,12,\,14,\,...\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20%7b10%7d%5e%7b1%7d,\,%7b15%7d%5e%7b1%7d,\,%7b20%7d%5e%7b1%7d,\,...\,&=&\,10,\,15,\,20,\,...%20\end%7beqnarray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\\text%7bThese%20answer%20choices%20do%20not%20yield%20the%20given%20pattern.%7d\\\text%7bTry%20the%20remaining%20choice.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\\begin%7barray%7d2(5),\,4(5),\,6(5),\,...&=&10,\,20,\,30,\,...%20%20\end%7barray%7d%20\\%20\end%7barray%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20\text%7bTherefore,%20the%20following%20pattern%20is%20the%20answer.%7d\\%20\vspace*%7b9%20\hspace*%7b-10%7d%7d%20\\%20%20%20\begin%7barray%7d%7bc%7d\hspace*%7b500%7d%20\\2n,\,4n,\,6n,\,...%20\\\end%7barray%7d

11. A generic arithmetic sequence is of the following form,

a , a + d , a + 2d , a + 3d , ... , a + (n - 1)d , ...

where a is the first term, d is the common difference, and a + (n - 1)d is the nth term.

In this case, the first term is 20 and the common difference is 7.

Therefore, the nth term is as follows.

nth term =

a + (n - 1)d

=

20 + (n - 1)(7)

=

20 + (7n - 7)

=

13 + 7n

12. The first and second differences of the sequence are shown below.

-5

-26

-61

-110

-173

\

/

\

/

\

/

\

/

-21

-35

-49

-63

\

/

\

/

\

/

-14

-14

-14


Since the second difference is constant, the pattern is quadratic with the form an2 + bn + c.

Set the second difference equal to 2a, and solve for a.

2a

=

-14

a

=

-7


Next, set the first term in the first difference equal to 3a + b, and solve for b.

3a + b

=

-21

3(-7) + b

=

-21

-21 + b

=

-21

b

=

0


Finally, set the first term in the pattern equal to a + b + c, and solve for c.

a + b + c

=

-5

-7 + 0 + c

=

-5

c

=

2


Therefore, the sequence can be represented by -7n2 + 2.

13. First, find the difference between terms.

22 - 18

= 4

26 - 22

= 4

30 - 26

= 4

34 - 30

= 4


Since the difference, 4, is constant, add 4 to the fifth term to find the next term.

34 + 4 = 38

14. First, find the difference between consecutive terms.

10 - 19

 = 

-9

1 - 10

 = 

-9

-8 - 1

 = 

-9


The difference between consecutive terms is -9.

Subtract 9 from -8 to find the fifth term, and then subtract 9 from the fifth term to find the sixth term.

-8 - 9

 = 

-17

-17 - 9

 = 

-26

15. First, find an expression that represents the nth term of the pattern.

The pattern starts with 16 and increases by 19 each time. Look at the sequence term by term to see if there is a recognizable pattern in terms of the position of the number in the sequence.

1st term:

16

 = 

19 · 1 - 3

2nd term:

35

 = 

19 · 2 - 3

3rd term:

54

 = 

19 · 3 - 3

4th term:

73

 = 

19 · 4 - 3


Therefore, the expression 19n - 3 represents the nth term in the pattern.

Substitute n = 8 into the expression and evaluate to find the eighth term of the pattern.

19(8) - 3 = 149

16. The common difference in a linear pattern is equivalent to the slope of the correlating line.

In the graph above, the slope is -2.

Therefore, the common difference of the correlating pattern is also -2.

The only answer choice with a common difference of -2 is
-5 , -7 , -9 , -11 , ....

17. Look at the sequence term by term and find a pattern in terms of number position.

n = 1,

# of dots =

4

= 1 × (1 + 3)

or 1 × 4

n = 2,

# of dots =

10

= 2 × (2 + 3)

or 2 × 5

n = 3,

# of dots =

18

= 3 × (3 + 3)

or 3 × 6


From looking at the patterns listed above, the number of dots is given by n × (n + 3).

Thus, the number of dots in the nth term of the sequence is given by n(n + 3).

18. A generic arithmetic sequence is of the following form,

a , a + d , a + 2d , a + 3d , ... , a + (n - 1)d , ...

where a is the first term, d is the common difference, and a + (n - 1)d is the nth term.

In this case, the first term is 39 and the common difference is 4.

Therefore, the nth term is as follows.

nth term =

a + (n - 1)d

=

39 + (n - 1)(4)

=

39 + (4n - 4)

=

35 + 4n

19. The volume for each solid can be determined by multiplying the number of cubes by the volume of each individual cube. Since the cubes each have a side length of e, the volume of each cube is e3.

Looking at the pattern, the number of cubes in each picture is always equal to c3.

Therefore, the total volume is given by c3 · e3.

20. Substitute values of n into each pattern to find which gives the same coordinates as those on the graph.

The pattern n2 - 5n - 3 matches the graph as shown below.

n

n2 - 5n - 3

(n, an)

0

(0)2 - 5(0) - 3 = -3

(0,-3)

1

(1)2 - 5(1) - 3 = -7

(1,-7)

2

(2)2 - 5(2) - 3 = -9

(2,-9)

3

(3)2 - 5(3) - 3 = -9

(3,-9)

4

(4)2 - 5(4) - 3 = -7

(4,-7)

5

(5)2 - 5(5) - 3 = -7

(5,-3)

6

(6)2 - 5(6) - 3 = -7

(6, 3)


Therefore, the graph represents the pattern n2 - 5n - 3 because the pattern gives the same coordinates as those on the graph.